Tubing for oil wells



Aug. 26, 1930.

H. A. BARDEEN TUBING FOR OIL WELLS Filed March 2,v 1926 HTTORMSY Patented Aug. 26 1930 UNITED STATES PATENT OFFICE HUGH A. BARDEEN,

OF LOS ANGELES, CALIFORNIA, ASSIGNOR TO B AND B PIPE SHOPS CORPORATION, 0]? LOS ANGELES, GALIFOENIA, A CORPORATION OF CALIFORNIA TUBING FOR OIL WELLS Application filed March 2, 1926. Serial No. 91,695.

My invention relates to the art of producing oil and more particularly to the art of pumping oil as it is practiced in the oil fields throughout the world.

It is common practice to line oil wells with steel pipe, commonly called casing, which is permanently fixed in place and which serves to support the walls of the well. In the case of flowing wells, the oil entering the casing through perforations near the bottom thereof is under sufficient pressure to flow naturally from the casing but inmost cases it is necessary to pump the oil which is usually done through a string of tubing which is hung in the well inside the casing and which carries a pump at its lower end. This pump is-actuated through a string of sucker rods extending down into the well and reciprocated by suitable mechanism at the surface of the ground. Whenever the pump needs inspection or repair it is necessar to remove the tubing from the well. practice, especially in the deeper wells, derricks over 100 feet high are erected over the upper end of the well and thetubing which comes in 20-foot lengths is joined together in stands consisting of two or more joints of tubing which are connected together by suitable couplings. It is quite common to use four or five joints to form a stand, the tubing as it is withdrawn from the well being stood up inthe corner of the derrick. During the last few years it has become necessary to go to constantly greater depths for oil and it is not unusualfor wells to be drilled to a depth of 5000 feet or more in the attempt to obtain oil from the lower oil measures. It is often necessary,

the drilling, to complete the lower portion of the well with comparatively small casing so that the diameter of the tubing which can be used is rather limited. Tubing of 3 inch diameter is quite common, and in some cases even smaller tubing is used. Since this tubing must be hung from its upper end, the weight of the tubing is so great that 1t 1nduces stresses of considerable magnitude in the upper portion thereof, especially 1n very deep wells. In the ordinary form of tubing which is of uniform inside and outside diamowlng to troubles during eter, it is common to cut threads on each end of each ]01I1t upon which the couplings are threaded. It is common practice to make the inside diameter of the tubing as large as possible and yet allow the collars upon the tublng to pass downwardly through the casing. In other .words, the maximum inside dlameter is determined by the thickness of the pipe and collar, and the outside diameter of the collar. It is found that the weakest portion of the tubing is at the threaded joint.

It is not unusual for the tubing to part at one means for coupling the tubing together which will in a large measure prevent these diflicuL ties.

' I have found that although new tubing properly made up into stands with new collars is fairly reliable, the frequent unscrewing of the oints as the tubing is taken out of the wells tends to wear and weaken the threads on the end of the tubing, thus further reducing its strength.

It is an object of my invention to provide means for connecting together stands of tubing which will be provided with threads capable of withstanding the frequent removal or replacement'of the tubing, these means in themselves being readily replaceable in the event the threads thereon become worn.

While it is possible to use seamless tubing or tubing formed of high tensile strength material, such tubing is more expensive than the ordinary lap welded pipe now in general use.

' It is a further object of my invention to strength and toughness.

between stands.

tion of t Further objects and advantages will be made evident hereinafter.

Referring to the drawings which are for diagrammatic purposes onl Fig. 1 shows a string of tubing as it hangs in the well just previous to breaking joints Fi 2 is a similar view showing a stand of tubing lifted away from the remainder of the string which is secured in the well.

Fig. 3 is a section through the improved form of tubing joint used by me in connection with my novel form of tubing stand.

In the form of the invention shown in these drawings, 11 is the casing of the well which is provided with a casin head 12 and a discharge pipe 13. The casing 11 is permanently set in place in the well. Oil is produced through a string of tubing 21 which is preferably made up in stands of three or four joints, the individual joints being connected to ether by means of standard collars 22 w ich are threaded to the pipe and which join it in stands of substantially uniform inside diameter. It is quite necessary that any means used for connecting the pipe be of substantially the same inside diameter as the tubing, since the clearance of the pump rods inside the tubing is rather small and anything projecting inwardly into the tubmg is liable to be caught by the plungerof the pum or the pump rods during the .operae pump or when the pump plunger is being withdrawn for repairs For the purpose .of joining together the different stands of tubing, I employ the tubing joint shown in Fig. 3 in which 31 is the lower joint of one stand and 32 is the upper joint of the adjacent stand. Secured by means of a thread 33 of the joint 31 is a primary member 34 which is of substantially the same outside diameter as the collars 22 and which has the same inside diameter as the tubing. A portion of the primary member 34 is however turned down to form a threaded extension 35 which has a straight shoulder 36 where it joins the body of the member 34. The member 34 is secured u n the lower end of the joint 31 and prefera ly forms the lower end of the stand as shown in Fig. 2. Secured to the upper end of the u per joint 32' of an ad'acent stand is a secon ary member 40 whic is secured on the joint 32 by threads 41 and which has a threaded cavity 42 adapted to receive the threaded' extension 35. I prefer to counterbore this cavity as shown at 43 and to provide it with a chamfered shoulder 44 which maybe screwed up solidly against the shoulder 36 as the stands are joined together. In Fig. 2 I show the upper stand of a string of easing which is resting upon the casing head 'bein held in a lower tubing elevator 50. Many orms of such tubing elevators are used in the art and they all pended from a hook 53. An upper elevator 54 is shown connected'under the secondary member 40 at the upper end of the stand. It

is evident that by pulling upwardly on the hook 53 the entire tubing may be suspended from the upper elevator and the lower elevator 50 removed, in which event the tubing may be lowered into the well until the elevator 54 rests upon the casing head, in which event a further stand may be secured in the string and the operation repeated.

In Figs. 1 and 2 it may be assumed that the tubing is being withdrawn from the well, in which event a workman using suitable tongs disconnects the primary member 34 from the secondary member 40 by holding the member 40. and turning the member 34 with the remainder of the stand. As soon as the member 34 is unscrewed from the secondary member 40, the tubing may be lifted into the position shown in Fig. 2 and stood in the corner of the derrick, the elevator being detached from the hook 53 which is lowered to grasp the hail of the elevator 50, the elevator 54 then being used as a lower. elevator to secure the next lower stand as it rises through the casing head 11.

The special form of tubing joint shown is preferably formed of special steel which may be readily heat-treated so that it is. much more resistant to wear than the ordinary tubing. The members 34 and 40 may be connected and disconnected repeatedly without serious wear on the threads on the projection 35 and these threads may be very accurately formed so that there is little danger of the tubing unscrewing.

By my invention I form a novel form of tubing stand having a threaded projection on one end and a threaded cavity on the other, this stand being of uniform inside diameter, which is substantially that of the pipe, and of uniform maximum outside diameter which is substantially that of the collars.

The remaining joints of each stand may be made up permanently with litharge and glycerine, red lead, or other self-hardening material so that they permanently set and will not unscrew. If after long use either of the members 34 to 40 show wear, they can be readily removed and new members substi tuted therefor so that the tubing has a practically unlimited life.

By the prbvision of the shoulders 36 and 44 I provide frictional means which when setup with suitable tongs resists rotation even under very considerable vibration and stress, and thus prevents unscrewing. My invention has come into very general commercial use and has proved of very great value in the oil industry.

I claim as my invention:

1. A combination comprising two stands of oil well tubing, and a tubing oint for connecting said stands together, said joint in- J cluding a primary member having about the same outside diameter as the maximum outside diameter of said stands and about the same inside diameter as said tubing, said primary memberhaving an externally threaded portion of a diameter greater thanthe internal diameter of said tubing and of a diameter less than the outside diameter of said primary member, said primary member having a threaded-cavity fitting over the threaded end of one stand of said tubing, and a secondary member having a threaded cavity in one end fitting over said externally threaded portion of said primary member and having a threaded cavity in the other end fitting over the threaded end of another stand, said secondary member having about the same outside diameter as said primary member, said threaded cavity in said secondary member which fits over said externally threaded portion of said primary member being counterbored for a short distance at its outer end so as to clear said threads on said externally threaded portion.

2. A combination comprising two stands of oil well tubing and a tubing joint for connecting said stands together, said joint including a primary member having about the same outside diameter as the maximum outside diameter of said stands and about the same inside diameter as said tubing, said primary member having an externally threaded portion of a diameter greater than the internal diameter of said tubing and of a diameter less than the outside diameter of said primary member, said primary member hav ing a threaded cavity fitting over the threaded end of one stand of said tubing; and a secondary member having a threaded cavity in one end fitting over said externally threaded portion of said primary member and having a threaded cavity in the other endfitting over the threaded end of another stand, said secondary member having about the same outside diameter as said primary member, said threaded cavity in said secondary member which fits over said externally threaded portion of said primary member being counterbored for a short distance at its outer end so as to clear said threads on said externally threaded portion, and said secondary memher having a chamfered outer end adapted to abut against a radial shoulder orLsaid primary member.

Intestimony whereof I have hereunto set mv hand at Los Angeles, California, this 20 day of February, 1926.

A. BARDEEN. 

